WEDNESDAY, Aug. 29 (HealthDay News) -- Mental deterioration occurs more quickly in women with Alzheimer's disease than in men with the devastating brain illness, a new study finds.

British researchers conducted a meta-analysis of 15 published studies of Alzheimer's patients and found that men consistently and significantly performed better than women in five tests of mental skills, even when they're at the same stage of the disease.

The investigators were surprised to find that even the verbal skills of women with Alzheimer's were worse than in men with the disease. This is different than among healthy people, where women have a distinct advantage over men in verbal skills.

Age, education levels and dementia severity did not explain the difference in mental decline between women and men, the authors noted.

The study appeared Aug. 24 in the Journal of Clinical and Experimental Neuropsychology.

"Unlike mental decline associated with normal aging, something about Alzheimer's specifically disadvantages women," study leader Keith Laws, a psychology professor at the University of Hertfordshire, said in a university news release.

"There has been some previous, but limited, evidence that females with Alzheimer's deteriorate faster than males in the earlier stages of the disease. And possible explanations are for a hormonal influence, possibly due to estrogen loss in women or perhaps a greater cognitive reserve in males which provides protection against the disease process. But further studies to examine sex differences with the disease are needed to provide greater clarity on these issues," Laws said.

Women are more likely than men to develop Alzheimer's and that difference increases with age, according to background information in the news release.